BIOM20002 Lecture Notes - Lecture 49: Cardiac Output, Heart Rate, Atrioventricular Node
Document Summary
Changes are fast (in one or 2 cardiac cycles) Baroreceptors: carotid sinus (senses blood going to brain which is important) & aortic. Can also directly stimulate parasympathetic to decrease heart rate and co. Respond rapidly: within 1 - 2 cardiac cycles stabilises pressure and smooths out variations. Hsf page 6 stabilises pressure and smooths out variations. Decreased map reduced stretch, reduced nerve firing augmented sympathetic tone heart - increased rate and contractility arteries - increased tpr. Hsf page 7 arteries - increased tpr withdrawal of cardiac parasympathetic tone - increased heart rate. Increased map since it eliminates effect of gravity increased stretch, increased nerve firing withdrawal of vascular sympathetic tone arteries - reduced tpr veins - reduced venous return augmented cardiac parasympathetic tone - reduced heart rate. How increased tpr? increased ecf - reduced renal salt excretion thickening of the arterial wall hypertrophy (may be pathology) high levels of vasoconstrictive hormones.
